Commit refs #799.

Example:
evsched_schedule_cb(server->sched, mycallback, data, 1000); // dt=1s

Commit refs #799.

Commit refs #799.

Commit refs #799.

Scheduler works with the same event type as evqueue_t.

Example:
evsched_t *s = evsched_new();
evsched_schedule_cb(s, myfunc, data, 1000) // Schedule myfunc() after 1000ms
event_t *ev = evsched_next(); // Run event scheduler
evsched_event_free(s, ev); // Free executed event
evsched_delete(s);

Commit refs #799.

- Renamed ns_parse_query() to ns_parse_packet().
- Renamed dnslib_query_t to dnslib_packet_type_t.
- ns_parse_packet() distinguishes between queries and responses.
- Added packet types for responses.

refs #801

Commit refs #757.

refs #782

Commit refs #757.

Implemented proposed format.
To do:
* think of shorter syntax for ACLs

Commit refs #757.

- Added parameter to response_add_rrset_*() functions to set
  dname compression case-sensitivity. (Changed API).
- Propagation of the parameter into all affected private functions.
- Changes in nameserver and response-tests to reflect the changed
  API.
- Changed the example zone file to contain domain names differing
  only in case of characters.

refs #776

- If case-sensitive, do not compare just pointers.

refs #776

- Added new API function.

refs #776

- Added parameter to response_add_opt() which determines if the
  max size will be overriden.

refs #769

- OPT RR adding to normal responses.
- OPT RR adding to AXFR. TODO: must somehow enforce larger packets
  than allowed by the OPT RR.
- Stopping AXFR when any error occurs (do not try to send NSEC3s).
- Real size of AXFR packets should not rewrite the buffer size in
  ns_xfr_t.
- Added a lot of debug output.

- Must retain Question section when clearing for AXFR.

fixes #781

- If both max size and OPT RR are given, the payload in the OPT RR
  cannot be larger than the max size - added check.
- Fixed API of response_add_opt().
- Disabled reallocation in response_add_opt() - larger size in OPT
  RR should not override the max size already set (max size is
  more important).

refs #769

refs #755

XFR handler uses event queue for receiving requests.
Each XFR handler thread asynchronously listens for events like UDP handler.

Commit refs #752.

Commit refs #736.

Commit refs #774.

refs #755

- Pointer must be less than 16383.

refs #755